1. Field of the Invention
This invention relates in general to certain new and useful improvements in snorkels, and more particularly, to snorkels of the type in which an underwater swimmer can adopt a variety of swimming positional attitudes without a fear of water inhalation.
2. Brief Description of the Prior Art
The snorkel is a very common breathing device for an underwater swimmer or diver. Most of the prior art snorkels are generally comprised of an elongate breathing tube which is adapted for generally vertical disposition when the diver is normally swimming in a prone position, i.e. parallel to the water surface. Usually, one end of the snorkel breathing tube is adapted for positioning above the water surface. A mouth piece is located on the opposite end of the snorkel breathing tube, e.g. below the water surface, for engagement by the teeth and lips of the user so that inhalation and exhalation can take place through the same elongate breathing tube.
In many of the prior art snorkels, the breathing tube was longer than desirable for efficient operation. As a result, exhaled carbon dioxide became trapped in the breathing tube upon exhalation as a result of a "head" of air above the carbon dioxide. This resulted in what is commonly known as "carbon dioxide build-up". This carbon dioxide was then re-inhaled in the next breath by the diver, thereby sacrificing oxygen intake which was needed.
In addition to the foregoing, the breathing tubes in these prior art snorkels were also of insufficient diameter, thereby causing the diver to exert a much greater amount of effort than should have been required in order to clear the breathing tube of water. Accordingly, during periods of high stress, the diver encountered deep breathing problems as a result of the higher oxygen demand. Moreover, the insufficient diameter of the breathing tube did not allow an unrestricted flow of air and/or water during clearing.
This type of prior art snorkel device is otherwise moderately effective so long as the attitude of the diver, that is, the position which the diver maintains relative to the water surface remains the same, that is, in a prone position. However, when the swimmer dives to a lower depth such that the upper end of the snorkel tube is under the water, or if the swimmer should change his diving attitude, such that he is vertical, or positioned at some angle with respect to the water surface, other than a horizontal or prone position, there is a tendency for the snorkel tube to fill with water.
In order to obviate this problem, there have been check valves and similar devices which have been proposed for use with snorkels to prevent the swimmer from inhaling water which may have accumulated in the snorkel tube and which valves or other devices are also adapted for purging water from the snorkel tube. Purging generally takes place by a large blast of expelled air from the swimmer which is presumed to force the water out of the snorkel tube when the swimmer has surfaced.
Exemplary of these prior art snorkels is U.S. Pat. No. 4,278,080 to Schuch which discloses a diving snorkel having a purge valve located in a bypass conduit. U.S. Pat. No. 3,768,504 to Reutsch, Jr., discloses a snorkel type breathing tube with a check valve to prevent ingress of water when the diver is submerged. U.S. Pat. No. 2,753,865 to Van Der Kogel discloses an underwater breathing device in the nature of a snorkel which may be disassembled for purposes of packing or storage and which includes a vertically extensible section.
There are other forms of prior art snorkels which include an elongate water column but which require exhalation efforts to clear water from the snorkel tube after re-emerging above the water surface. There are other types of snorkels which include traps of types to preclude water from being inhaled by the diver, regardless of the diving positional attitude. One of the more pertinent of these prior art snorkels is hereinafter described in more detail.
In substance, many of the previous commercially available prior art snorkels failed the practical test of usage and therefore, have had a very short market availability. In large measure, many of the prior art designs were inadequate as a result of long or narrow breathing tubes which thereby increased the difficulty in clearing the tube or which resulted in carbon dioxide build-up. Several designs incorporated valves, such as flapper valves, ball-check valves, etc. While the designs appeared to be adequate from a design consideration, they did not overcome many of the problems which were inherent in the prior art as a result of valve sticking, improper proper valve seating, or the like. Moreover, sand or other debris became an obstruction which prevented proper seating and hence sealing. As a result, these prior art snorkels were not fully effective for their intended purposes.